Power is another area that can become very crunchy very quickly – and frankly it can be a big headache calculating whether that laser revolver had enough power to shoot six shots or only five. The easiest way I have found to work through such a problem is to start with a single consistent common thing you intend to use power for in your game – say, one shot of a common weapon – and refer to that as a pulse, then work backwards to sort out what kind of battery you need to generate that pulse, and worry about the crunchy bits only if it's important.